Heat transfer apparatus



D. COE

HEAT TRANSFER APPARATUS Filed March 15, 1965 FIG! //VVE/V70/P THOMAS D. COE

ATTORNEYS United States Patent 3,313,339 HEAT TRANfiFER APPARATUS Thomas D. Coe, Winchester, Mass, assignor to Wakefield Engineering Company, Wakefieid, Mass, a corporation of Massachusetts Filed Mar. 15, 1965, Ser. No. 439,753 4 Claims. (Cl. 165-80) The present invention relates in general to heat transfer apparatus and more particularly concerns a novel semiconductor cooling device that is relatively inexpensive to fabricate, occupies a relatively small portion of the chassis area and may be readily cooled from the top or any side by forced or natural convection.

It is an important object of this invention to provide apparatus for cooling semiconductor devices efiiciently while occupying a relatively small portion of the chassis area and 1 eing capable of affording cooling through natural or forced convection from any side and from the top.

It is another object of this invention to achieve the preceding object with a device that is relatively easy and inexpensive to fabricate in large quantities.

According to the invention, a base plate is formed of material of high thermal conductivity, such as aluminum. A plurality of fins are arranged generally perpendicular to the base plate with the plane of each fin extending from the perimeter of the base plate in a radial plane extending from the center of the base plate. The central portion of the base plate and the inside edges of the fins define a volume for accommodating a semiconductor device to be cooled. The separation between adjacent fins is preferably less than the length of each fin.

Numerous other objects, features and advantages of the invention will become apparent from the following specification when read in connection with the accompanying drawing in which:

FIG. 1 is a perspective view of an embodiment ac cording to the invention; and

FIGS. 2 and 3 are top and side views, respectively, thereof.

With reference now to the drawing, there is shown a preferred embodiment of the invention comprising a unitary structure with a square base plate 11 supporting sixteen upwardly extending fins 12 with the plane of each fin perpendicular to the base plate 11 in a radial plane extending from the perimeter 13 toward the center 14 of the base plate. The inside edges 16 of fins 12 and the central portion 15 of base plate 11 define a volume of generally circular cross section for accommodating a semiconductor device to be cooled. The central 14 may be tapped or punched to accommodate the stud of a semiconductor device which may be of diameter corresponding to that of the generally circular cross section defined by the inside edges 16 to better accommodate a semiconductor device to one diagonal of the base plate may be formed With inside edges 16 outside a circle defined by the other inside edges 1 6to better accommodate a semiconductor device formed with diametrically opposed b-ase end tabs. The separation "between adjacent fins is less than the height of each fin.

The preferred method of forming the devices according to the invention is through the well-known technique of impact extrusion in which a slug of hot viscous lubricated aluminum is placed in a die and struck by a mating punch to form essentially a device according to the invention with some rough edges that may be removed through standard techniques, such as milling. Other techniques may be employed to form a device according to the invention.

The invention has a number of advantages. It occupies a relatively small amount of chassis area. For a given chassis area occupied, fin area may be increased by lengthening the fins or spacing them closer together. Forced or natural convection may be efiected by air or other fluid fiowing through the fins from any side or upon the device from the free ends of the fins with the coolant flowing out through the fins on any or all of the sides. A specific embodiment of the invention that has actually been constructed by impact extrusion is made from aluminum with the base plate 11 being essentially a square 1 on a side and thick with the fins 1 high and /s" thick. The diameter of the circle bounded by the inside edges 16 is of the order of 1% The specific embodiment described herein is by way of example only for illustrating the best mode now contem plated for practicing the invention. The shape and size of the base plate and fins may be varied without departing from the principles of the invention.

It is apparent that those skilled in the art may now make numerous modifications of and departures from the specific embodiment described herein Without departing from the inventive concepts. Consequently, the invention is to be construed as limited solely by the spirit and scope of the appended claims.

What is claimed is:

1. Apparatus for cooling a semiconductor device comprising,

a conducting plate of material of high thermal conductivity, a plurality of fins of material of high thermal conductivity perpendicular to and in good thermal contact with said plate,

each fin extending from the perimeter of said plate with the plane of each fin essentially in a radial plane emanating from the center of said plate,

the edges of said fins inside of said perimeter coacting with the central portion of said plate to define a volume for supporting a semiconductor device to be cooled with said fins defining radial passages extending from said volume to the outside of said perimeter along the entire perimeter length with each radial passage from said volume to said perimeter embraced along the entire passage length by an embracing pair of said fins,

the separation between adjacent fins being less than the height of each fin.

2. Apparatus in accordance with claim 1 wherein said perimeter is essentially square,

and the edges of said fins inside of said perimeter de fine a volume of essentially circular cross section.

3. Apparatus in accordance with claim 1 wherein said fins and said conducting plate are of same material of high thermal conductivity and make up an integral structure formed by impact extrusion.

4. Apparatus in accordance with claim 3 wherein said perimeter is essentially square,

and the edges of said fins inside of said perimeter define a volume of essentially circular cross section.

References Cited by the Examiner UNITED STATES PATENTS 2,535,669 12/1950 Clay -80 X 3,135,321 6/1964 Butt et al. 165154 X 3,180,404 4/1965 Nelson et a1 16547 ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner. 

1. APPARATUS FOR COOLING A SEMICONDUCTOR DEVICE COMPRISING, A CONDUCTING PLATE OF MATERIAL OF HIGH THERMAL CONDUCTIVITY, A PLURALITY OF FINS OF MATERIAL OF HIGH THERMAL CONDUCTIVITY PERPENDICULAR TO AND IN GOOD THERMAL CONTACT WITH SAID PLATE, EACH FIN EXTENDING FROM THE PERIMETER OF SAID PLATE WITH THE PLANE OF EACH FIN ESSENTIALLY IN A RADIAL PLANE EMANATING FROM THE CENTER OF SAID PLATE, THE EDGES OF SAID FINS INSIDE OF SAID PERIMETER COACTING WITH THE CENTRAL PORTION OF SAID PLATE TO DEFINE A VOLUME FOR SUPPORTING A SEMICONDUCTOR DEVICE TO BE COOLED WITH SAID FINS DEFINING RADIAL PASSAGES EXTENDING FROM SAID VOLUME TO THE OUTSIDE OF SAID PERIMETER ALONG THE ENTIRE PERIMETER LENGTH WITH EACH RADIAL PASSAGE FROM SAID VOLUME TO SAID PERIMETER EMBRACED ALONG THE ENTIRE PASSAGE LENGTH BY AN EMBRACING PAIR OF SAID FINS, THE SEPARATION BETWEEN ADJACENT FINS BEING LESS THAN THE HEIGHT OF EACH FIN. 